How to match--but not capture--in Python regular expressions?

I've got a function spitting out "Washington D.C., DC, USA" as output. I need to capture "Washington, DC" for reasons that have to do with how I handle every single other city in the country. (Note: this is not the same as "D.C.", I need the comma to be between "Washington" and "DC", whitespace is fine)

I can't for the life of me figure out how to capture this.

Here's what I've tried:

    >>>location = "Washington D.C., DC, USA"

    >>>match = re.search(r'\w+\s(?:D\.C\.), \w\w(?=\W)', location).group()
    >>>match
    u'Washington D.C., DC'

Is not (?: ...) supposed to just match (and not capture) "D.C."?

Here are the 2.7.2 Docs:

(?:...) A non-capturing version of regular parentheses. Matches whatever regular expression is inside the parentheses, but the substring matched by the group cannot be retrieved after performing a match or referenced later in the pattern.

What gives??

Thanks in advance!